基于隐式IB-LBM的二维搅拌摩擦焊接模拟

A 2D Friction Stir Welding Simulation Based on Implicit Immersed Boundary-lattice Boltzmann Method

本文首次采用隐式浸入边界格子Boltzmann方法(IB-LBM)对二维搅拌摩擦焊接过程中的输运现象及搅拌头受力状况进行数值模拟与分析。两个不同的多松弛方程被分别用来求解速度场及温度场,搅拌头受力由浸入边界法计算得到。采用一种可移动的分块网格技术加密变形区域。搅拌头-工件界面考虑部分黏着/滑移接触条件,并通过模拟得到的扭矩计算产热量,形成工艺内部产热的自适应。结合实验数据,分析了2024-T3铝合金焊材的热量物质流动特性以及搅拌头受力特点。讨论了搅拌头转速及焊接速度对产热以及搅拌头受力影响。另外,研究发现三平面搅拌针作用下的搅拌区域明显大于圆形搅拌针。

The transport phenomena with tool force for friction stir welding(FSW)process were firstly simulated and analyzed by implicit immersed boundary-lattice Boltzmann method(IB-LBM).Two multiple-relaxation-time(MRT)equations were employed to solve the flow field and the temperature field,respectively.The tool forces were acquired by IBM,and a shifting multi-block method was employed to refining the grids in the moving deformation region.A partial sticking/sliding contact condition was considered at the tool-workpiece interface,and the heat density there was updated by the tool torque which forming an adaptive heat production process.Combined with experimental data,the thermal and material flow behaviors of aluminum alloy 2024-T3 as well as the feature of tool forces were analyzed.The effects of both the rotating speed on the heat generation and the welding speed on the traversing force were discussed.In addition,the comparison between the conical and trifiat tools was performed with focus on their affected deformation zone.This work is expected to provide theoretical support and basic data for the application of FSW in aluminum alloy lightweight structural welding forming manufacturing.